This invention relates generally to gasket seal for a fluid dispenser mounted with the use of a freely rotatable closure cap threaded onto the neck of the container of product to be dispensed, and more particularly to such a gasket providing an interference fit between the cap and the container neck for increasing resistance to cap backoff.
U.S. Pat. No. 5,072,860, commonly owned herewith, discloses a sealing gasket having slip resistance means on opposing sides for engagement with like means on the lower edge of the pump body and the upper edge of the container neck to avoid slippage of the gasket seal which thereby prevents loosening of the tightened closure cap from the container neck which may cause leakage.
U.S. Pat. No. 4,325,487 discloses a thread cap having an internal helical fin to provide a wedging torque-controlled securement of the cap to the container.
U.S. Pat. No. 3,421,648 discloses a paper insert having projections along the periphery which fold along a securing band to permit removal of the insert as part of a storage assembly for a home food processing closure.
U.S. Pat. Nos. 1,682,234, 1,882,278 and 3,371,813 disclose closure lid sealing gaskets of various types.
U.S. Pat. No. 5,337,928 discloses a gasket seal having holes through which posts on the pump body extend for attaching the gasket to the lower end of the pump body for retaining the gasket within the freely rotatable closure cap.
The trigger sprayer is typically mounted on the container by provision of a freely rotatable, internally threaded closure cap which is torqued down over the external threads of the container neck. A gasket seal of elastomeric material is disposed in sealing engagement between the lower edge of the pump body and the upper edge of the container neck for sealing against leakage. The gasket seal normally has an outer diameter equal to the outer diameter of the container neck, and has an opening through which the dip tube extends from the pump body into the container. As shown in the U.S. Pat. No. 5,072,860, the gasket seal may be retained within the closure upon engagement with a tube retainer. Otherwise, the gasket seal may be attached to the pump body as in the U.S. Pat. No. 5,337,928.
During shipping, storage and handling of the dispensing package, the threaded closure oftentimes loosens, thereby presenting leakage problems. The approach taken in the U.S. Pat. No. 5,072,860 to resist rotation of the dispenser body in a loosening direction is satisfactory, although the ratchet teeth or other form of slip-resistant means must be formed on the gasket seal and cooperating parts of the dispensing package which requires additional molding steps, adding to the cost of production.
The present invention provides a simple and economical, yet highly effective approach in resisting cap backoff, which thereby avoids leakage after the closure cap is torqued down over the container neck using an intervening portion of the gasket seal. The gasket seal, according to the invention, is oversized relative to the inner dimension of the closure cap, such that the gasket seal is frictionally retained within the cap for free rotation together therewith, and a portion or portions of the oversized gasket is bent by the cap to lie between the cap and the container neck upon thread tightening the cap on the container neck. The gasket seal has a predetermined thickness to form an interference fit between the cap and the container neck for increasing resistance to cap backoff.
The gasket seal may have a non-circular shape such as octagonal, rectangular, or the like, forming interference protrusions, or may be provided with one or more tabs or ears providing protrusions forming the interference fit.
The gasket seal protrusions of elastomeric material are deformed by the threads on the cap and/or on the container neck for positively resisting torque backoff and thereby avoiding leakage of product from the container.
Other objects, advantages and all features of the invention will become more apparent from the following detailed description of the invention when taken in conjunction with the accompanying drawings.